Given the date of the poem (1895) and the fact that
it was in 1893 that Lobengula attacked the British settlers and miners, I agree
with Mary Hamer that Lobengula (King of the Matabele tribe (Ndebele) in
what is now Zimbabwe) is the most likely answer.
'Google' doesn't react to 'Loben' except with some
incomprehensible (to me) German pop singer!
And Sayyid Burgash was a bad tempered Sultan of
Zanzibar (see 'The Limitations of Pambe Serang' in Life's
Handicap - I'm cheating, it's Google again!). The British had just
had a certain amount of trouble with him on the East African coast.
Yours,
Alastair
Wilson